The invention relates generally to a mounting apparatus for studying blast attenuation of layered panels from gas gun exposure. In particular, the invention provides a gas gun interface mount to enable response testing at normal and oblique incidence angles of layered panels.
Conventional methods of measuring blast wave propagation through materials have involved the use of small explosive charges or a gas gun equipped with a Mylar burst diaphragm to generate the blast wave and complex target geometries such as instrumented mannequin heads wearing helmets coated with different test materials. There are three key disadvantages to these techniques:
(1) explosive charges pose safety and environmental hazards,
(2) the repeatability of Mylar burst diaphragms is poor at low pressures (below 100 psi), and
(3) complex target geometries introduce uncertainties in the data due to irregular flow of the blast wave around targets and into the interfaces between the helmets and the instrumented mannequin heads.
U.S. Pat. No. 8,935,963 (issued Jan. 20, 2015) addresses these disadvantages by adapting a simplified target geometry to an existing gas gun equipped with a fast-opening valve. Even though that reference describes a much improved method compared to traditional methods for low pressure blast wave measurements, several limitations remain. These include:
(1) test material blast area diameters are limited to only 2.5″ (inches), which in turn limits the thickness of the materials to be tested due to edge release waves interfering with the longitudinal blast wave;
(2) the impact surface of the test materials can be positioned only normal to the blast wave, which precludes the important non-normal blast region from being investigated; and
(3) because the target materials are located inside a tight-fitting polymethyl methacrylate (PMMA) tube for testing, fragile target strain gauge leads must be carefully threaded in a restrictive PMMA slot to exit the target assembly for attaching to measurement instrumentation.